Radio Propagation - Modes

Modes

Radio frequencies and their primary mode of propagation
Band Frequency Wavelength Propagation via
ELF Extremely Low Frequency 3–300 Hz 1000-100,000 km
VLF Very Low Frequency 3–30 kHz 100–10 km Guided between the earth and the ionosphere.
LF Low Frequency 30–300 kHz 10–1 km Guided between the earth and the D layer of the ionosphere.

Surface waves.
MF Medium Frequency 300–3000 kHz 1000–100 m Surface waves.

E, F layer ionospheric refraction at night, when D layer absorption weakens.
HF High Frequency (Short Wave) 3–30 MHz 100–10 m E layer ionospheric refraction.

F1, F2 layer ionospheric refraction.
VHF Very High Frequency 30–300 MHz 10–1 m Infrequent E ionospheric (Es) refraction. Uncommonly F2 layer ionospheric refraction during high sunspot activity up to 50 MHz and rarely to 80 MHz. Generally direct wave. Sometimes tropospheric ducting.
UHF Ultra High Frequency 300–3000 MHz 100–10 cm Direct wave. Sometimes tropospheric ducting.
SHF Super High Frequency 3–30 GHz 10–1 cm Direct wave.
EHF Extremely High Frequency 30–300 GHz 10–1 mm Direct wave limited by absorption.

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